Aspects of the present disclosure relate generally to wireless communication networks, and more particularly, to cell selection by an user equipment.
Wireless communication networks are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. For example, a fifth generation (5G) wireless communications technology (which can be referred to as new radio (NR)) is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, 5G communications technology can include: enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with certain specifications for latency and reliability; and massive machine type communications, which can allow a very large number of connected devices and transmission of a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, further improvements in NR communications technology and beyond may be desired.
Any user equipment (UE) may be configured to maintain the connection to the best possible cell to achieve faster throughputs and better coverage. Sometimes when a UE encounters an out of sync or a radio link failure (RLF) event, there is a significant loss to the downlink and uplink data transmissions. Especially in millimeter wave (mmW)/5G technology, where the radio conditions can change rapidly, RLF/out of sync scenario is expected to be seen more frequently once deployed. In Non-Standalone (NSA) cases as well, if a UE in LTE experiences a RLF event, this will have a double loss since both the LTE and NR connection will have to be torn down. UEs not having any robust mechanism to recover faster will suffer a unacceptable loss in the data throughputs and also might delay camping on the best cell.
In NR communications, connections between the UE and the base station (BS) may be lost due to a variety of technological and environmental factors, such as out of sync and RLF events. For example, in millimeter wave 5G technology, the radio conditions can change rapidly, which may cause RLF and/or out of sync incidents. In Non-Standalone 5G cases, since the UE anchors the connection on existing LTE infrastructure, a lost connection may cause network delays because the UE may reconnect to both LTE and NR. Lost connections may lead to interruptions in the network access of the UE, dropped phone calls, loss in data throughputs, and in general, lower overall user satisfaction. Therefore, improvements may be desired to handle these situations.